1. Field
The present disclosure generally relates to molded plastic outlet boxes which are attached to an electric busway power distribution system at each location along the system, wherein the outlet boxes comprise press fit connectors for connecting each outlet box to an aluminum housing of the electric busway. Preferably, each outlet box include wings on each side thereof to provide a snap-fit retention against the side walls of the aluminum busway housing.
2. Discussion of the Background Art
Electric busway distribution systems comprise a plurality of rectangular bus bar conductors arranged within a metallic housing for providing electric power to industrial buildings. Every two feet or so, the bus bars are provided with upstanding contact blades to allow for connection with a power take-off assembly. One such power distribution system is described within U.S. Pat. No. 4,758,172 filed Oct. 13, 1987 entitled “Power Distribution Busway System”. This patent application describes contact blades extending from the individual phases of a multi-phase power distribution system that are arranged for electrical connection with a power take-off assembly. In this arrangement, the contact blades are formed from the bus bar conductors themselves. U.S. patent application Ser. No. 203,751 entitled “Insulated Electrical Power Distribution Busway Tabs” describes the use of off-set tabs welded to the individual bus bars to provide the stabs for connecting with power take-off assemblies. U.S. patent application Ser. No. 122,863 filed Nov. 19, 1987 entitled “Thermally Efficient Power Busway Housing” describes a power busway housing design that is used with the molded case outlet box of the instant invention. All of the aforementioned U.S. patent applications are incorporated herein for purposes of reference.
U.S. Pat. No. 4,714,431 entitled “Electrical Distribution System Having an Improved Plug-In Assembly for Current Tap-Off” describes the bus bar conductors that are spaced apart at periodic intervals for the insertion of the receiver stabs. The base portion of the plug-in assembly includes insulating means extending between the individual bus bars for electric isolation.
U.S. Pat. No. 4,820,178, which is incorporated herein by reference in its entirety discloses a conventional outlet box for use with an electric busway system which affixed to the aluminum housing via four (4) screws. FIG. 1 describes such a conventions electric busway system, wherein the bus conductors 11 of the type consisting of a rectangular bar 12 of aluminum or copper are each provided with an electrically insulating epoxy coating 13 and are arranged within a continuous housing 14 consisting of first and second side frames 15, 16 which support the bus bars as well as provide ground conduction to the busway section. The bus bars are not “bumped” or otherwise separated at each plug-in section as indicated at 7 and 8 herein to facilitate connection with a power take-off assembly (not shown). Instead, welded contact blade tabs such as 20-23 are off-set from each other to accommodate connection with the power take-off assemblies. The contact blade tabs that are welded to the individual bus bars and the epoxy coating is removed from a part of the tabs to provide good electrical connection therewith. The contact blade tabs extend above the cross-piece 18 that joins the upstanding rails 17 on the first and second side frames 15, 16 that make up the busway section 10 through corresponding cross-piece slots 19. The busway sections and bus bars are fastened together by means of thru-bolts 9 provided through the busway section where the plug-in sections 7, 8 are located. In order to electrically isolate the upstanding contact blade tabs 20-23, a molded plastic plug-in enclosure 6 is arranged over the contact blade tabs by means of threaded openings 26 formed on the cross-piece 18 and by means of bolts or screws 24 and thru-holes 25. One such molded plastic plug-in enclosure already attached to the plug-in section 8 is depicted at 6′ to indicate the electrical isolation of the contact blade tabs 20-23 therein. The plug-in enclosure 6 consists of a molded plastic base 27 formed from a phenylene-oxide plastic sold by General Electric Company under the trademark “NORYL” or a polybutylene terepthalate which is sold under the General Electric trademark “Valox”. The base is molded to include a planar bottom, not shown, through which the thru-holes 25 are formed. Also formed within the planar top are opposing channels, not shown, which accommodate a ground lug that is separately attached to the busway section 10 along the cross-piece 18. A molded plastic cover 40, which includes a planar top portion 40A and downwardly depending side portions 40B and 40C, is attached to the base 27 by means of a pivot post 41 integrally formed therein and extending between a pair of tabs 42, 43. The cover is attached to the base by positioning the pivot post 41 under a pair of curvilinear projections 32 extending from the planar top 33.
The above busway plug-in outlet insulator utilizes four screws or bolts 24 to mount the outlet to aluminum housing or busway 10. Such mechanical mounting of the outlet to the housing or busway via screws or bolts is very disadvantageous and requires a substantial increase in manufacturing labor and materials. The present disclosure overcomes these disadvantages by providing a easy mounting devices to allow for rapid and cost effective mounting of the outlet to the housing or busway, without the need for extensive labor required by conventional systems to screw mount the outlet via four (4) bolts.
The present disclosure also provides many additional advantages, which shall become apparent as described below.